Concrete: How thin can I pour it and still have it hold together? I am putting up a small chicken coop this fall and of flooring options I think concrete would be the easiest to maintain (hoses out well). The pad (concrete) will be small maybe 5 feet by 10′ (maybe 4′ x 8’not sure yet). But what I was thinking is to pour it about 3.5″ thick around the perimeter but only have it 1-2″ in the middle. Slight slope with some grooves for water/uck draining. Will this work or will it just bust up in a year or so with the chickens dancing about. I think the heaviest thing in there will be me with omelet plans.
Replies
Something that small, I'd just form the sides with 2x4's and fill 'em up. I wouldn't go under 2" with it unless you had fiber reinforcing in there, or some other kind of high-strength concrete. I know the universities build concrete canoes in their civil engineering programs, and they get down to 1/2" thickness, but it's a heavily reinforced ultra high strength concrete mix.
IMO it depends on how well the slab is supported compared to the load it has to carry. I have seen people pour concrete on bedrock less than an inch thick for the interior of a home. Essentially the slab is on a surface that has no flex and the load is minimal.
On the other hand I have seen a 4" fiber and mesh reinforced slab crack and split when the expansive clay expanded unevenly leaving large spans unsupported. Even though the concrete was reinforced more than the code required it still split and left some splits with a one inch elevation difference.
The home had to be rebuilt.
I have heard 2" being used as a rule-of-thumb minimum. I assume a reasonable amount of reinforcement, support and load is built into this general rule.
the area is so small you are not talking any money on extra concrete. the minimum charge would cover that. go 4 inches.
Check with some local mix truck vendors. They may have a minimum order, perhaps half a yard. That would be enough to cover your 5x10 area a little over 3" thick.
-- J.S.
4" x 5' x 10' is only 17cuft or 2/3yd. That is 25-32? bags of redy-crete. Less than a minimum order from a batch plant.
If it was my chicken coop, I would form with 2x4s, level and dampen the ground the day before the "pour." The next day I would fill the form with dry redy-crete and compact it with my handy garden roller compactor.
Mist the top of the crete til I've seen water stand on every spot for 3 (three) seconds, trowel it if needed, then cover it with visqueen and dirt seal the edges and sprinkle some soil around the field to keep the visqueen in contact with the mud.
It will be walkable in 24 hours and workable in 72. Frame the walls right over the visqueen, and leave it down till the last minute (chickens.) Then cut it out leaving the strip under any framing as a moisture barrior.
If I went 2" (this is a coop, not a shed) I would second compact it with a vibrating shoe compactor and put chicken wire down on the first 1" of compacted dry crete. If it's stable soil, forget the wire.
IMO, moistened in place crete takes twice, or more, as long to cure, can only be used in damp soils, and is stronger, has fewer cracks, and is more water tight than poured mud.
SamT
but 25-32 bar of crete would be more than 2 yd of concrete delivered and already mix.
No ,this is readycrete 60# bag . Every thing in it execept water. A bag of portland is 90# ,you add the sand gravel. But you knew that . Right.
I think BB means they would cost more.
Around here, 30 bags 60# redi-mix runs about $75, a yard is about $75. 6, 12/2
SamT
Around here, 30 bags 60# redi-mix runs about $75, a yard is about $75. 6, 12/2
Hmm, lets see, do I want to drive over to box store and sift through 2 palletes of concrete to find 30 good bags (ooh, that one is split open, that one is leaking, that one got wet). Hoist 30, 60lbs bags into the truck. Then hoist them back out when you get home. Then one by one mix them up (or two by two)....
Or what is behind door #2? I call up the concrete place and have them deliver a yard or two at 11 AM. My phone is lighter than 30 bags of redi-mix. I'm lazy that way ;)jt8
.
Where I live, the 90# bags of premixed concrete state on the bag that it produces 2/3 cubic foot of concrete when mixed with water. This translates into 41 bags equals a cubic yard. A 60# bag should produce 2/3 of what a 90# bag does, or 4/9 a cubic foot (just under a half.) So 61 bags of 60# size to pour a yard of mud. The truck sounds better all the time!
Had a friend who, in an obstinate mood refusing to pay for a commercial delivery, mixed two cubic yards, his estimate, by hand with nothing but a deep wheel barrow and a mason's hoe, the one with the holes.
He started in the morning and finished in the afternoon. He came into be bar almost too pooped to pick up his beer. He couldn't move his shoulders he had worked them so hard. It was a couple of days before he was 'right' again. Good thing his girlfriend was a massage therapist.
After that if a job called for more than a few bags he called in the truck. Even if it meant his neighbors got free walkways with the left over from a minimum load.
Concrete is wonderful stuff. While I'm not ready to turn my yard into a parkinglot, I do think there are GOBS of things you can do with a 'bit of extra' concrete.jt8
I've seen more than one chicken coop that later became a greenhouse, a storage shed, a woodshed or a small barn.
That coupled with the fact that concrete is still one of the least expensive building materials on the planet, I would, without hesitation, pour a slab of 4" with probably a perimeter footing.
If you're pouring hand-mixed sacrete bags, maybe you can skimp by, but if you're going to order ready mix, you're probably going to be paying a 2 1/2 or 3 yard minimum anyway ( $210 in my neighborhood).
So pour a slab with some future versatility and maybe form up for some pier blocks or a sidewalk or something, call for a minimum order and get your money's worth!
Edited 10/6/2004 12:15 am ET by Notchman
As already mentioned you will need less than a yard of concrete for this job. If I were doing it, I would pick up a 1 yard dump cart, the kind you pull behind your truck and pour it myself. Around here (Texas) that would cost around $100 bucks or so. Oh yeah, are put is some wire, just in case you want to build something else there later.